The primary goal of this research is to develop and implement novel luminescent metal-to-ligand charge transfer (MLCT) compounds as extrinsic biophysical probes. The luminescence properties of these compounds can be dramatically altered and well controlled with variation of the lignads and/or metal center. This coupled with the favorable characteristics of MLCT compounds (visible absorbance bands, high quantum yields, long lifetimes, and polarized emission) makes them ideal candidates for use in biophysical spectroscopy. Thee compounds provide a unique opportunity to explore biophysical phenomena on time scales that are largely unexplored. Initial studies will focus on the factors which control the emission anisotropy of MLCT compounds. This will be followed by the synthesis of MLCT compounds which have conjugatable ligands for attachment to biomolecules. Each compound will be designed with specific intrinsic properties such as long wavelength luminescence or extremely long lifetime. All dynamical measurements will be performed in a complimentary manner, in both the time and frequency domain.